1. Field of Art
The present invention relates to securing of a shadow mask and a substrate for depositing one or more layers of materials on the substrate.
2. Description of the Related Art
Various chemical processes are used to deposit material on a substrate. Such chemical processes include chemical vapor deposition (CVD), atomic layer deposition (ALD) and molecular layer deposition (MLD). CVD is the most common method for depositing a layer of material on a substrate. In CVD, reactive gas precursors are mixed and then delivered to a reaction chamber where a layer of material is deposited after the mixed gas comes into contact with the substrate.
ALD is another way of depositing material on a substrate. ALD uses the bonding force of a chemisorbed molecule that is different from the bonding force of a physisorbed molecule. In ALD, source precursor is absorbed into the surface of a substrate and then purged with an inert gas. As a result, physisorbed molecules of the source precursor (bonded by the Van der Waals force) are desorbed from the substrate. However, chemisorbed molecules of the source precursor are covalently bonded, and hence, these molecules are strongly adsorbed in the substrate and not desorbed from the substrate. The chemisorbed molecules of the source precursor (adsorbed on the substrate) react with and/or are replaced by molecules of reactant precursor. Then, the excessive precursor or physisorbed molecules are removed by injecting the purge gas and/or pumping the chamber, obtaining a final atomic layer.
MLD is a thin film deposition method similar to ALD but in MLD, molecules are deposited onto the substrate as a unit to form polymeric films on a substrate. In MLD, a molecular fragment is deposited during each reaction cycle. The precursors for MLD have typically been homobifunctional reactants. MLD method is used generally for growing organic polymers such as polyamides on the substrate.
In order to perform such deposition methods on a substrate, the substrate may be placed below a shadow mask onto a susceptor in a deposition device. The susceptor may move across reactors, selectively exposing portions of the substrate corresponding to patterned areas of the shadow mask to different materials and radicals injected by the reactors. Although it is preferable to maintain a short distance between the reactors and the substrates during the movement, deformations and protruding components (e.g., shadow mask) in the deposition device may limit further reducing of the distance between the reactors and the substrates.